Added TouchID/FaceID to sign in

Splits/DocsView.swift

@@ -6,9 +6,10 @@
 //
 
 import SwiftUI
-// this file will not have comments.
-// this code is considered simple enough to be
-// human-readable without aid, as long as
+import LocalAuthentication
+// this file will have some comments.
+// Most of this code is considered simple enough
+// to be human-readable without aid, as long as
 // the reader has a basic understanding of
 // Swift and/or SwiftUI.
 
@@ -23,7 +24,8 @@ struct DocsView: View {
 	
 	@State private var pass: String = ""
 	@State private var user: String = ""
-	@FocusState private var focusedField: Field?
+	@State private var isUnlocked = false
+ 	@FocusState private var focusedField: Field?
 	
 	var body: some View {
 		NavigationView {
@@ -44,24 +46,38 @@ struct DocsView: View {
 				}
 				Section(header: Text("App Information")) {
 					NavigationLink("Software License", destination: LicenseView())
-					Text("Version: Release Candidate (1.0.0)")
-					Text("Release date: 2022-06-10")
+					Text("Version: Release Candidate 2 (1.0.0)")
+					Text("Release date: 2022-06-11")
 					Text("Start date: 2022-03-25")
 					Link("Built with SwiftUI \(Image(systemName: "swift"))", destination: URL(string: "https://developer.apple.com/xcode/swiftui")!)
 				}
 				Section(header: Text("Login")) {
-					SecureField("Username", text: $user)
-						.keyboardType(.alphabet)
-						.textContentType(.username)
-						.submitLabel(.next)
-						.focused($focusedField, equals: .username)
-					SecureField("Password", text: $pass)
-						.keyboardType(.numbersAndPunctuation)
-						.textContentType(.password)
-						.submitLabel(.done)
-						.focused($focusedField, equals: .password)
-					if (pass == password && user == username) {
+					if (isUnlocked) {
 						NavigationLink("Contacts", destination: SecretView())
+						Button("Log out") {
+							pass = ""
+							user = ""
+							isUnlocked = false
+						}
+					} else {
+						if !isUnlocked {
+							Button("Log in with biometrics") {
+								authenticate()
+							}
+						}
+						SecureField("Username", text: $user)
+							.keyboardType(.alphabet)
+							.textContentType(.username)
+							.submitLabel(.next)
+							.focused($focusedField, equals: .username)
+						SecureField("Password", text: $pass)
+							.keyboardType(.numbersAndPunctuation)
+							.textContentType(.password)
+							.submitLabel(.done)
+							.focused($focusedField, equals: .password)
+						if checkPassword() {
+							NavigationLink("Contacts", destination: SecretView())
+						}
 					}
 				}
 			}
@@ -74,8 +90,48 @@ struct DocsView: View {
 				default:
 					()
 			}
+			if (pass == password && user == username) {
+				isUnlocked = true
+			}
 		}
 	}
+	func checkPassword() -> Bool {
+		if (pass == password && user == username) {
+			return true
+		} else {
+			return false
+		}
+	}
+	func checkIfUnlocked() {
+		if !isUnlocked {
+			authenticate()
+		}
+	}
+	func authenticate() {
+		let context = LAContext()
+		var error: NSError?
+
+		// check whether biometric authentication is possible
+		if context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error) {
+			// it's possible, so go ahead and use it
+			let reason = "We need authentication before we can show you sensitive data"
+
+			context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { success, authenticationError in
+				// authentication has now completed
+				if success {
+					isUnlocked = true
+				} else {
+					()
+				}
+			}
+		} else {
+			()
+		}
+	}
+	// getting this to work came from
+	// https://www.hackingwithswift.com/books/ios-swiftui/using-touch-id-and-face-id-with-swiftui
+	// a truly epic website and it's helped me with
+	// just about all of my code questions
 }
 
 struct DocsView_Previews: PreviewProvider {